【摘要】：能源需求的增加使有限的化石燃料枯竭的負(fù)擔(dān)變得更加沉重,為了尋找環(huán)保、可再生的綠色能源,克服未來能源的焦慮,政府鼓勵科學(xué)家們尋找新的可代替能源。氫作為一種新型綠色資源,具有零碳排放、能量密度高以及高能量轉(zhuǎn)換效率的特點(diǎn)。電解水制氫是零碳排放、大規(guī)模產(chǎn)生氫的重要技術(shù)之一。但是高純度、大規(guī)模地生產(chǎn)氫具有一定難度,因?yàn)殡娊馑磻?yīng)實(shí)際需要一個較高的電位,約為1.8-2 V。這明顯大于理論分解電壓1.23 V。這個電勢電位與催化活性相關(guān),被用來在陽極電極發(fā)生析氧反應(yīng),在陰極發(fā)生析氫反應(yīng)。因此,活性好、效率高的催化劑必須要在合理的電流密度下,減少電極過電位以確保電解水反應(yīng)過程變得更節(jié)能。到目前為止,對析氫反應(yīng)來說,鉑及類以鉑為基礎(chǔ)的材料是最好的催化劑。Pt在微不足道的過電位下表現(xiàn)出較高的陰極電流密度。然而,貴金屬及其化合物屬于稀缺性資源,并且成本較高,這限制了其大規(guī)模的應(yīng)用。大多數(shù)的以非貴金屬氧化物為基礎(chǔ)的電極材料迄今少有作為析氫和析氧的雙功能催化,高活性催化劑的報(bào)道。這是因?yàn)橥浑娊赓|(zhì)環(huán)境下,不適當(dāng)?shù)木w結(jié)構(gòu)會使電極材料導(dǎo)電性降低,從而阻礙其在全水分解過程中的適用性。因此,設(shè)計(jì)并構(gòu)筑具有具有特定形貌結(jié)構(gòu)的高活性、高耐用性、價格低廉的非貴金屬催化劑成為當(dāng)下研究的熱點(diǎn)。本文結(jié)合當(dāng)下非貴金屬催化劑的研究現(xiàn)狀,主要做了以下兩方面的進(jìn)展工作:(1)構(gòu)筑了 一種新型三維Cu2O @ MnO2核/殼納米線陣列結(jié)構(gòu)電極�；谌S網(wǎng)狀導(dǎo)電基底泡沫銅,在其表面生長Cu2O納米線陣列作為核芯材料,MnO2納米片作為包覆層材料。性能優(yōu)異的的Cu2O @ MnO2 NW/NS陣列具有很高的催化活性和很強(qiáng)的耐久性。在電流密度為10mA/cm2時,過電位為132 mV(相對于標(biāo)準(zhǔn)析氫電位)。這是純錳氧化物/氫氧化物催化劑活性應(yīng)用于的析氫反應(yīng)的第一個示范。此外,仔細(xì)分析和表征后,我們發(fā)現(xiàn)Cu2O@Mn02NW/NS高活性主要來源于水鈉錳礦型MnO2(δ-MnnO2)到Mn(OH)2的演變。在電催化反應(yīng)中,Mn(OH)2的是高度活躍的析氫催化劑。這些研究結(jié)果將為其他錳基催化劑的探索提供了新的試驗(yàn)與理論依據(jù)。(2)構(gòu)筑一種簡便的方法在泡沫鎳表面原位制備活性高、多層次結(jié)構(gòu)的NiCo2O4納米線@NiCo02納米線樹枝狀結(jié)構(gòu)�；谌S網(wǎng)狀導(dǎo)電基底泡沫鎳,得到的電極材料表現(xiàn)出分層的樹枝狀結(jié)構(gòu),其中NiCo2O4納米線為骨干,NiCoO2納米線的分支。所制備的NiCo2O4 @NiCoO2 NW/NW納米材料具有顯著的催化活性和良好的耐久性。在1MKOH電解液中,當(dāng)電流密度為10mA/cm2時,析氫過電位為165 mV,析氧過電位為291 mV,全水分解電壓為1.756 V。這是NiCo2O4@NiCoO2 NW/NW復(fù)合樹枝狀結(jié)構(gòu)的用作雙催化功能的電極材料在堿性溶液中的第一次報(bào)告。本論文的方法提供了一種簡便的方式來探索新的納米催化劑的應(yīng)用。
[Abstract]:The growing demand for energy has added to the burden of limited fossil fuel depletion. In an effort to find green, renewable energy and overcome future energy worries, the government has encouraged scientists to look for new alternative sources of energy. As a new green resource, hydrogen has the characteristics of zero carbon emission, high energy density and high energy conversion efficiency. Hydrogen production from electrolytic water is one of the most important technologies to produce hydrogen on a large scale and zero carbon emission. However, it is difficult to produce hydrogen on a large scale with high purity, because the electrolytic water reaction needs a high potential of about 1.8-2 V. This is obviously larger than the theoretical decomposition voltage of 1.23 V. This potential is related to catalytic activity and is used for oxygen evolution at the anode electrode and hydrogen evolution at the cathode. Therefore, the catalyst with good activity and high efficiency must reduce electrode overpotential at reasonable current density to ensure that the process of electrolytic water reaction becomes more energy efficient. So far, platinum and platinum-based materials are the best catalysts for hydrogen evolution. Pt exhibits high cathodic current density at negligible overpotential. However, precious metals and their compounds are rare resources and high cost, which limits their large-scale application. Most electrode materials based on non-noble metal oxides are rarely reported as bifunctional and highly active catalysts for hydrogen evolution and oxygen evolution. This is because under the same electrolyte environment, improper crystal structure will reduce the conductivity of electrode material, thus hindering its applicability in the whole water decomposition process. Therefore, the design and construction of high activity, high durability and low cost non-precious metal catalysts with specific morphology have become a hot topic. According to the current research status of non-noble metal catalysts, the following two advances have been done: (1) A novel three-dimensional Cu2O @ MnO2 nanowire array electrode has been constructed. Cu2O nanowire arrays were grown on the surface of three dimensional netted conductive substrates, and Cu2O nanowires were used as core-core materials and MnO2 nanochips as coating materials. The excellent Cu2O @ MnO2 NW/NS array has high catalytic activity and durability. When the current density is 10mA/cm2, the overpotential is 132 mV (relative to the standard hydrogen evolution potential). This is the first demonstration of the application of pure manganese oxide / hydroxide catalyst activity to hydrogen evolution. In addition, after careful analysis and characterization, we found that the high activity of Cu2O@Mn02NW/NS is mainly due to the evolution from MnO2 (未-MnnO2) to Mn (OH) 2. , Mn (OH) _ 2 is a highly active catalyst for hydrogen evolution in electrocatalytic reactions. These results will provide a new experimental and theoretical basis for the exploration of other manganese based catalysts. (2) A simple method for in-situ preparation of nickel foams has high activity. Multilevel NiCo2O4 nanowires @ NiCo02 nanowire dendrites. Based on the three dimensional netted conductive substrate nickel foam, the electrode material shows a layered dendritic structure, in which NiCo2O4 nanowires are the backbone and NiCoO2 nanowires are branched. The prepared NiCo2O4 @ NiCoO2 NW/NW nanomaterials have remarkable catalytic activity and good durability. In 1MKOH electrolyte, when the current density is 10mA/cm2, the overpotential of hydrogen evolution is 165 mV, oxygen evolution overpotential is 291 mV, the total water decomposition voltage is 1.756 V. This is the first report of the NiCo2O4@NiCoO2 NW/NW composite dendritic structure used as a double catalytic electrode material in alkaline solution. The method in this paper provides a simple way to explore the application of new nano-catalysts.
【學(xué)位授予單位】：北京交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：O643.36;TQ116.2

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本文編號：2333879